Mailing List Archive: mod_backhand: users

multiple backhand clusters on one subnet?

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liamr at umich

Mar 14, 2003, 11:39 AM

Post #1 of 5 (1147 views)
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multiple backhand clusters on one subnet?

We're considering using mod_backhand for load balancing on our cluster of
webmail servers. As we're also considering backhand for load balancing on the
servers that host our directory client, we only want them sharing their
candidacy information with other servers in the same service (eg mail requests
shouldn't get shunted to a directory server and vice versa).

The IP addresses for each service are non-contiguous, and both are on the same
subnet. Is it possible to place the machines in separate pools? If so, how?

thx
Liam

liamr at umich

Mar 14, 2003, 11:54 AM

Post #2 of 5 (1098 views)
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Re: multiple backhand clusters on one subnet? [In reply to]

D'oh. byHostname would fulfill this, wouldn't it?

I did run into a problem where requests were getting bounced between port 80 on
machine and 443 on another. The backhand directives were in the top level of
the apache conf file. Would placing them in the virtualhost blocks prevent this?

Liam

Quoting Liam Hoekenga <liamr [at] umich>:

> We're considering using mod_backhand for load balancing on our cluster of
> webmail servers. As we're also considering backhand for load balancing on
> the
> servers that host our directory client, we only want them sharing their
> candidacy information with other servers in the same service (eg mail
> requests
> shouldn't get shunted to a directory server and vice versa).
>
> The IP addresses for each service are non-contiguous, and both are on the
> same
> subnet. Is it possible to place the machines in separate pools? If so,
> how?
>
> thx
> Liam
>

jesus at omniti

Mar 14, 2003, 11:35 PM

Post #3 of 5 (1091 views)
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multiple backhand clusters on one subnet? [In reply to]

Yes.

If you want them truly separate, then just specify different ports on
the MulticastStats line.

On Friday, Mar 14, 2003, at 13:39 US/Eastern, Liam Hoekenga wrote:

> We're considering using mod_backhand for load balancing on our cluster
> of
> webmail servers. As we're also considering backhand for load balancing
> on the
> servers that host our directory client, we only want them sharing their
> candidacy information with other servers in the same service (eg mail
> requests
> shouldn't get shunted to a directory server and vice versa).
>
> The IP addresses for each service are non-contiguous, and both are on
> the same
> subnet. Is it possible to place the machines in separate pools? If
> so, how?

--
Theo Schlossnagle
Principal Consultant
OmniTI Computer Consulting, Inc. -- http://www.omniti.com/
Phone: +1 410 872 4910 x201 Fax: +1 410 872 4911
1024D/82844984/95FD 30F1 489E 4613 F22E 491A 7E88 364C 8284 4984
2047R/33131B65/71 F7 95 64 49 76 5D BA 3D 90 B9 9F BE 27 24 E7

jesus at omniti

Mar 14, 2003, 11:37 PM

Post #4 of 5 (1096 views)
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Re: multiple backhand clusters on one subnet? [In reply to]

No. You need to specify the two argument version of MulticastStats
line and specify a port. Or you can do what I do and just fiddle with
your Listen lines and make sure everything shows up as port 80 on the
/backhand/ page.

On Friday, Mar 14, 2003, at 13:54 US/Eastern, Liam Hoekenga wrote:
> D'oh. byHostname would fulfill this, wouldn't it?
>
> I did run into a problem where requests were getting bounced between
> port 80 on
> machine and 443 on another. The backhand directives were in the top
> level of
> the apache conf file. Would placing them in the virtualhost blocks
> prevent this?
--
Theo Schlossnagle
Principal Consultant
OmniTI Computer Consulting, Inc. -- http://www.omniti.com/
Phone: +1 410 872 4910 x201 Fax: +1 410 872 4911
1024D/82844984/95FD 30F1 489E 4613 F22E 491A 7E88 364C 8284 4984
2047R/33131B65/71 F7 95 64 49 76 5D BA 3D 90 B9 9F BE 27 24 E7

liamr at umich

Mar 15, 2003, 11:00 AM

Post #5 of 5 (1082 views)
Permalink

Re: multiple backhand clusters on one subnet? [In reply to]

On Saturday, March 15, 2003, at 01:37 AM, Theo Schlossnagle wrote:

> No. You need to specify the two argument version of MulticastStats
> line and specify a port. Or you can do what I do and just fiddle with
> your Listen lines and make sure everything shows up as port 80 on the
> /backhand/ page.

Hm... I am specifying port 80 and curiously the backhand status page
reports one listening to 443 and the other on 80, and neither seem to
be referring connections to the other (even if add "Backhand
removeSelf" to one of the conf files and restart the server).

We've got an entire class C subnet. On one machine, the multicast
line looks like:

MulticastStats 141.xxx.yyy.83:80 141.xxx.yyy.255:4445,1

Otherwise, it's identical to the IfModule block below.
Here's what I've added to our conf files. It occurs outside of any
virtual host block:

<IfModule mod_backhand.c>
UnixSocketDir /var/apache/run
MulticastStats 141.xxx.yyy.74:80 141.xxx.yyy.255:4445,1
AcceptStats 141.xxx.yyy.0/24

<Location "/backhand/">
SetHandler backhand-handler
</Location>

<Directory "/usr/local/umweb/cgi-bin">
AllowOverride None
Options None
Order allow,deny
Allow from all
Backhand byAge
Backhand byRandom
Backhand byLogWindow
Backhand byLoad
</Directory>
</IfModule>

The two machines in question have identical apache installations (down
to the conf files).

The IP addresses we're specifying are not the primary addresses for
these machines. Most of our servers have at least one virtual
interface (the primary is reserved for administrative purposes, any web
hosts on a machine will be on a virtual interface - either by itself or
in a named virtual host group) . What we're trying to do is to get
backhand to listen on one specific interface, at one specific port.
Right now, that's port 80, eventually it'll only be port 443. We're
using Apache 1.3.27, Solaris 8 (SPARC), and mod_backhand from CVS (I
couldn't get 1.22 to build).

Any ideas on what I'm doing wrong?

Liam

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